I. Field
The following description relates generally to wireless communications, and more particularly to responses to an overload indicator in a wireless communication system.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems can be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access systems can include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), ultra mobile broadband (UMB), multi-carrier wireless specifications such as evolution data optimized (EV-DO), one or more revisions thereof, etc.
Generally, wireless multiple-access communication systems can simultaneously support communication for multiple user equipments (UEs). Each UE can communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to UEs, and the reverse link (or uplink) refers to the communication link from UEs to base stations. Further, communications between UEs and base stations can be established via single-input single-output (SISO) systems, multiple-input single-output (MISO), multiple-input multiple-output (MIMO) systems, and so forth. In addition, UEs can communicate with other UEs (and/or base stations with other base stations) in peer-to-peer wireless network configurations.
Heterogeneous wireless communication systems commonly can include various types of base stations, each of which can be associated with differing cell sizes. For instance, macro cell base stations typically leverage antenna(s) installed on masts, rooftops, other existing structures, or the like. Further, macro cell base stations oftentimes have power outputs on the order of tens of watts, and can provide coverage for large areas. The femto cell base station is another class of base station that has recently emerged. Femto cell base stations are commonly designed for residential or small business environments, and can provide wireless coverage to UEs using a wireless technology (e.g., 3GPP Universal Mobile Telecommunications System (UMTS) or LTE, 1x Evolution-Data Optimized (1xEV-DO)) to communicate with the UEs and an existing broadband Internet connection (e.g., digital subscriber line (DSL), cable) for backhaul. A femto cell base station can also be referred to as a Home Evolved Node B (HeNB), a Home Node B (HNB), a femto cell, an access point base station, or the like. Examples of other types of base stations include pico cell base stations, micro cell base stations, and so forth.
To maintain uplink performance in a wireless communication system, interference caused by UE(s) in neighboring cell(s) (e.g., UE(s) served by respective serving base station(s)) can be monitored. For instance, interference over thermal (IoT) can be measured by a non-serving base station. Moreover, tight IoT control can be achieved by the non-serving base station using an overload indicator. According to an example, the non-serving base station can measure an interference level caused by an uplink transmission sent by a UE in a neighboring cell (e.g., served by a serving base station). Following this example, if the interference level exceeds a threshold, the non-serving base station can generate an overload indicator that signifies that the non-serving base station is overloaded on the uplink.
Conventionally, the overload indicator is sent between base stations over a backhaul via an X2 interface. Pursuant to the above example, the non-serving base station that generates the overload indicator based upon interference caused by the UE served by the serving base station can send the overload indicator over the backhaul to the serving base station. Further, the serving base station can control a transmit power level of the UE served thereby using a power control command generated based upon the overload indicator received over the backhaul. In common approaches, the response to the overload indicator received by the serving base station over the backhaul can be dependent upon base station implementation.
However, in a heterogeneous wireless communication system, a backhaul can be lacking. For example, the X2 interface may not be available between a femto cell base station and a macro cell base station. To address the foregoing, over-the-air transmission of an overload indicator can be leveraged. Thus, the non-serving base station that generates the overload indicator can transmit the overload indicator over-the-air to the serving base station. Further, the serving base station (e.g., femto cell base station) can have receiver capability similar to a UE. Moreover, if the overload indicator is sent over-the-air, the UE can also receive the overload indicator in addition to reception by the serving base station. However, conventional approaches typically fail to reconcile responses to the power control command received by the UE from the serving base station and the overload indicator received over-the-air from the non-serving base station.